1. Field of the Invention
The invention relates to an apparatus which controls braking force that is generated during coasting of a vehicle, and a method thereof.
2. Description of the Related Art
As related art of the invention, art for enhancing fuel economy by stopping a fuel supply in an area in which an engine rotational speed is equal to or higher than a predetermined value during coasting of a vehicle, more particularly, during deceleration has been known. An example of the art is disclosed in Japanese Patent Laid-Open Publication No. 2000-255284. In a control apparatus of a vehicle which is disclosed in this publication, a power transmission path is configured such that engine power is transmitted to a differential through a forward backward switching mechanism and a continuously variable transmission. Also, a torque converter and a lockup clutch are provided in parallel between an engine and the forward backward switching mechanism.
During deceleration of the vehicle, the lockup clutch is connected, and the fuel supply to the engine is cut off until a predetermined vehicle running state is realized. Then, when the predetermined vehicle running state is realized, the lockup clutch is disconnected, and the fuel supply is started. At the time of starting the fuel supply, an amount of fuel supply is controlled such that an engine output is increased and exceeds an idling maintaining output by a predetermined amount. By performing such control, a torque difference between before and after the disconnection of the lockup clutch can be reduced, and shock caused due to a change in vehicle speed can be decreased.
However, in the control apparatus disclosed in the abovementioned publication, there is a problem that since an amount of the fuel supplied at the time of disconnecting the lockup clutch becomes larger than an amount of the fuel supplied at the idling time of the engine, fuel economy deteriorates.